test/reorder: fix double free of drained buffers

[ upstream commit d51955ea93fba1873e9c2b86a911e114787bdd4d ]

Set to zero array of drained buffers after free, to prevent freeing them
one more time.
Discovered with enabled `RTE_LIBRTE_MEMPOOL_DEBUG`.

Fixes: ecd867f ("test/reorder: fix freeing mbuf twice")

Signed-off-by: Volodymyr Fialko <vfialko@marvell.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>

app/test/test_reorder.c

@@ -270,6 +270,7 @@ test_reorder_drain(void)
 	}
 	if (robufs[0] != NULL)
 		rte_pktmbuf_free(robufs[0]);
+	memset(robufs, 0, sizeof(robufs));
 
 	/* Insert more packets
 	 * RB[] = {NULL, NULL, NULL, NULL}
@@ -306,6 +307,7 @@ test_reorder_drain(void)
 		if (robufs[i] != NULL)
 			rte_pktmbuf_free(robufs[i]);
 	}
+	memset(robufs, 0, sizeof(robufs));
 
 	/*
 	 * RB[] = {NULL, NULL, NULL, NULL}